As a kind of a technique of forming a film on a substrate, a plasma enhanced atomic layer deposition (PE-ALD) method has been known. In the PE-ALD method, a substrate is exposed to a precursor gas containing constituent elements of a thin film to be formed so that the precursor gas is chemically adsorbed to the substrate. Subsequently, the substrate is exposed to a purge gas to remove the precursor gas excessively chemically adsorbed to the substrate. Then, the substrate is exposed to plasma of a reaction gas containing constituent elements of a thin film to be formed to form a desired thin film on the substrate. In the PE-ALD method, such steps are repeated, so that a film, in which atoms or molecules contained in the precursor gas are processed, is generated on the substrate.
As an apparatus for performing the PE-ALD method, a semi-batch type film forming apparatus has been known. In the semi-batch type film forming apparatus, a region for supplying a precursor gas and a region for generating the plasma of a reaction gas are separately formed in the processing chamber and the substrate passes through the regions in sequence, so that a desired film is generated on the substrate.
The film forming apparatus includes a placing table, an injecting unit, and a plasma generating section. The placing table supports the substrate and is rotatable around a rotational axis. The injecting unit and the plasma generating section are disposed to face the placing table and arranged in the circumferential direction. The injecting unit has a substantially planar fan shape and supplies the precursor gas. The plasma generating section supplies the reaction gas and radiates microwaves supplied from a waveguide placed in a plane direction of a plate-shaped antenna from a substantially fan-shaped antenna, thereby generating plasma of the reaction gas. An exhaust port is formed around the injecting unit and around the plasma generating section and an injection port for supplying purge gas is formed on the periphery of the injecting unit. Further, a round antenna may be used in the plasma generating section. See, for example, International Publication No. WO 2013-122043.